The Theory And Application Study Of Energy Quality Upgrading Of Industrial Heat Pump

Under the given conditions,the essential of energy application is the application of energy quality.Once the energy quality fails to meet the established application conditions,it can be regarded as invalid energy.There are two ways for invalid energy:either to be continuously used into the application field that demand lower working conditions,which mainly involving the cascade utilization of energy;or to improve its energy quality to meet the requirements of established conditions.Nowadays,almost50% of industrial consumption will be exhausted as waste heat into the environment,which causing a huge amount of energy waste.Meanwhile,the demands of the heat arrange from 100-160 ℃ is gradually increasing in the industrial fields.In hence,the energy quality upgrading technology is investigated to deal with the conflict between high energy consumption demands and low energy conversion rate.Among of several technology processes,the single-stage high temperature heat pump system can be used to deal with the working condition with low temperature difference,while the cascade heat pump system can be used to that with high temperature difference.Therefore,the energy quality upgrading technology is a promising technique.In this work,we first designed a theoretical route,that is,the selection of working fluid of high-temperature heat pump,fluid and solid coupling,and the optimization of thermal system.On basis of theoretical route,we briefly and clearly introduced the principles and the energy balance equations of single-stage high temperature heat pump system and cascade heat pump system,respectively.Some key problems in this technology had been analyzed in theoretically.As for case analysis,we take an ejector as an energy quality upgrading equipment,a numerical method based on fluid and solid coupling effect are proposed to calculate the detail structure of the ejector nozzle and diffuser section.Noteworthy this method is not only applicable into both pure and mixed working fluid,but also overcomes the limitation and inaccuracy of empirical formula.In correspondingly,based on the optimization requirement of high temperature condition,the fluid of BY6 are developed.We investigated that the refrigerants of BY3B/BY6 group with the cascade heat pump system in theoretically.And the maximum temperature of the condensing water could up to 168.4 ℃ from the experimental aspect,which is the maximum heating temperature of the heat pump system at present.The temperature lift of the two stages system could be reached to113.4 ℃.Noteworthy,the COP of the system would reach to 2.86 when the promoted temperature reached to 70 ℃,which is higher than other single-stage heat pump system.Furthermore,on basis of working fluid of BY6,this work proposed a novel and simplified detects method based on the utilization of simultaneously adjusted ejector system and the balance of energy-mass to detect the performance of a 312 kW industrial scale high temperature open type non-oil double screw compressor.This method replaced the traditional devices of cooling/heating resource and heat exchanger,which would save around 94.5% construction cost.This method is first proposed around the world.The mentioned method had been tested by the built-up experimental equipment,whose experimental results indicated that the highest discharge temperature of the designed compressor could be reached at 184.8 ℃,isentropic efficiency was around 70%,volumetric efficiency was around 90%.In a view of the production processes of a methanol recovery tower and semi-regeneration reforming pre-hydrogenation unit in a petrochemical enterprise,the author puts forward the technical methods of improving the quality of waste heat by using single-stage and cascade heat pump systems respectively,to achieve regeneration and reuse.The coupling system was analyzed from 4E(Energy,Exergy,Economy and Environment).According to the completed results,the modify of industrial unit based on the heat pump system is not only satisfied all technical requirements,but also had certain economic benefits and environmental performance.On consideration of the punishment cost of residual gas emission,the minimum payback period time of coupling single stage heat pump and coupling cascade heat pump system is only 0.3 years and 0.36 years,respectively.